Rubber compositions containing a layered compound are known for their improved material properties, which is achieved by separating the layers (nanosheets with high aspect ratio) composing the layered compound and dispersing the separated layers in the rubber composition. However, the layers of the layered compound are generally not readily separated due to the attracting force of electric charges between the layers, resulting in poor dispersibility of the layers in the rubber composition. To solve this problem, for example, Patent Literature 1 (PTL 1) proposes a rubber composition that contains a complex and a solid rubber, in which the complex is composed of a liquid rubber having positively charged groups and a layered silicate (dispersed in the liquid rubber). PTL 1 reports that such a rubber composition has superior mechanical characteristics, oil resistance, fatigue resistance, and processability. However, it is not always easy to prepare the liquid rubber that incorporates onium ions as positively charged groups as described in PTL 1. Moreover, even if technique of PTL 1 is successfully employed, swelling between the layers of the layered compound, and therefore the separation of the layers of the layered compound, is often insufficient, which may often lead to the failure to provide expected physical properties.